The present disclosure relates generally to air data systems, and more particularly to air data systems utilizing multi-function probes and static pressure ports for generating aircraft air data parameters.
Modern aircraft often incorporate air data systems that calculate air data outputs based on measured parameters collected from various sensors positioned about the aircraft. For instance, many air data systems utilize air data probes that measure pneumatic pressure of oncoming airflow about the aircraft exterior to generate aircraft air data outputs, such as angle of attack (i.e., an angle between the oncoming airflow or relative wind and a reference line of the aircraft, such as a chord of a wing of the aircraft), calibrated airspeed, Mach number, altitude, or other air data parameters. During sideslip of the aircraft (i.e., a nonzero angle between the direction of travel of the aircraft and the aircraft centerline extending through the nose of the aircraft), compensation of various local (to the probe) parameters or signals, such as angle of attack and static pressure, is advantageous for accurate determination of aircraft air data parameters, such as aircraft angle of attack or aircraft pressure altitude (determined from static pressure measurements).
Increased accuracy achieved through sideslip compensation is particularly relevant when the aircraft operates in Reduced Vertical Separation Minimum (RVSM) space areas of air traffic control systems. To this end, many air data systems utilize multiple pneumatic air data probes positioned at opposite sides of the aircraft and cross-coupled to exchange pressure information. Static pressure sensed by an opposite side probe is used to compensate air data parameter outputs for a sideslip condition. In certain air data systems, cross-coupled probes are pneumatically connected so that the pressure signals are averaged between probes. Other air data systems utilize air data probes that are not pneumatically connected, but rather include processors and other electronic components for interchanging electrical signals representative of the pressure information (and other information) between probes. Such probes, having integrated electronics, are often referred to as electronic multi-function probes (MFPs). MFPs reduce the need for pneumatic couplings between the probes, thereby reducing space, cost, and maintenance associated with the pneumatic couplings.
As aircraft systems such as flight control systems and stall protection systems become more highly integrated, complex, and automated, the integrity of air data information used by these aircraft systems becomes increasingly important. As such, these highly complex systems typically utilize redundant inputs of air data information that are measured by independent sources. The independent sources of air data are often desired to be derived from dissimilar equipment to reduce the risk of common mode errors occurring amongst the separate sources of air data. This redundancy, independence, and dissimilarity of air data outputs is strongly recommended by certification authorities in the United States and Europe, among others. Indeed, adherence to one of varying levels of redundancy, independence, and dissimilarity requirements is typically required for airworthiness certification of the aircraft, the level of requirement often determined by, e.g., the type of aircraft and the complexity of the systems consuming the air data. Accordingly, certain aircraft air data systems can benefit from an air data system architecture that provides a high level of availability of air data parameters from independent and dissimilar sources, but without the increased cost, space, and weight of three, four, or more electronic MFPs.